The invention to transferring data between buses in a computer system. In particular, the invention relates to a bus bridge for transferring data between buses, to a DMA controller for transferring data between buses, to a computer system incorporating such a bus bridge and/or DMA controller and to a method of transferring data between buses.
In the present context, a bridge is a mechanism for transferring data between buses. It is commonplace in modem computer systems for multiple buses to be provided, and for a bridge mechanism to be provided for transferring data between the buses. The bridge mechanism may take many different forms and may incorporate other functions. For example, it is known to provide a DMA controller between an I/O bus and another bus forming part of the computer system.
For different buses, it may be desirable to have different byte address alignments. The present invention addresses the problem of providing efficient transfer between buses with selectable bus alignment on the respective buses.